1. Field of the Invention
The present invention relates to a float valve device configured so that a float can come up in a housing when a height of a liquid level of a liquid rises to thereby close an opening portion communicating with an outside when the liquid level reaches a predetermined height. In particular, the present invention relates to one suitable as a float valve device configured so as to dissipate fuel vapor contained in a fuel tank of an automobile to a canister, to prevent fuel from flowing outside of the fuel tank by closing the opening portion when a height of a liquid level of the fuel exceeds a predetermined value, and to regulate the fuel tank from being filled up at the time when the fuel tank is refueled.
2. Description of the Related Art
For example, in a fuel tank of an automobile, there is disposed a float valve device for preventing an inner pressure of the fuel tank from increasing by dissipating fuel vapor contained in the fuel tank to a canister disposed outside thereof, for preventing fuel from flowing outside of the fuel tank by closing an opening portion communicating with the canister when a height of a liquid level of the fuel exceeds a predetermined height, and for regulating the fuel tank from being filled up at the time when the fuel tank is refueled.
Japanese Patent Application Laid-Open No. Hei 07-279789 discloses, as such a float valve device, a liquid level control valve, which includes: a seat section (corresponding to a valve seat) including a first planar portion disposed in an opening portion of a fuel tank connected to one end of a passage in which the other end is connected to a canister; a valve member having a first planar portion abutting on the first planar portion of the seat section; and a float that floats in the fuel tank by buoyancy of the fuel, and pushes the valve member upward by a top portion thereof in response to a rise of a fuel level, and thereby allows the valve member to abut on the seat section, thus making it possible to close the opening portion of the fuel tank. It is further described that the valve member is engaged with the float so as to be freely movable relatively thereto, and that the top portion of the float includes a protruding portion formed of a three-dimensional curved surface formed on an upper central portion of the float.
The liquid level control valve of the above-mentioned in Japanese Patent Application Laid-Open No. Hei 07-279789 is configured so that the top portion of the float pushes the valve member upward, whereby the top portion of the float can be allowed to abut on the seat section and thereby can close the opening portion. Accordingly, even if a position of the float is inclined with respect to the opening portion owing to inclination and the like of a vehicle, the valve member movable relatively to the float abuts on the seat section so as to be adapted thereto, and accordingly, there is obtained an advantage that sealing performance can be stably obtained.